The Determination Of The Amount Of Nitrogen Fertilizer For The Recommended Major Rice Varieties And The Study Of Nitrogen Response In The Jilin Province

Jilin province is a main grain production area and an important commodity grain base of the country which has made tremendous contribution to guarantee national grain security and matain balance between food supply and demand.Grain economy effects social economic development and the development of the Old Industrial Bases,which is the premise of further reform and development of Jilin province.Rice plays an important role in grain production,with high economic value.In recent years with the rapidly expanding of paddy fields area and the total output growing,social and economic benefits are remarkable.With the steady development of agricultural production,Jilin province adjusts the Agricultural Production Structure to high -yield,high-quality and high-benefit.With the market economy situation,planting trends to diversification from singleness,at the same time rice production accounts for an increasing proportion in grain production.As the new development of rice growing area,a series of fertilizing problems come out,which effect rice production and the increase of yield.The increase of rice production is far less than the rate of nitrogen fertilizer volume increases in large area production.Excessive application of nitrogen fertilizer not only reduces nitrogen fertilizer use efficiency and increase the cost of agricultural production,but also caused eutrophication of surface water and groundwater in dangerously high levels of nitrate,and other environmental problems.Thus,improve nitrogen responsivity,determin optimum rate of application,decrease nitrogen fertilizer losses and play the effect on agriculture production are important to reduce the agricultural production cost and protect environment,also promote Agricultural Sustainable Development.This experiment selected 5 rice cultivars(Huijing7,Tongxi158,Nongda19,Jijing88 and Fengyou307) which are main cultivars in south of Jilin province.By field experiments the test cultivars were finally determined Huijing7,Tongxi158,Nongda19,Jijing88 and Fengyou307.Their separate yield is:10637kg/hm~2, 10421kg/hm~2,10654kg/hm~2,11064kg/hm~2,10919kg/hm~2,their corresponding volume of nitrogen is:160.0 kg/hm~2,214.4 kg/hm~2,161.3 kg/hm~2,207.4kg/hm~2 and 172.7 kg/hm~2;best nitrogen volume is 145.2kg/hm~2, 193.5kg/hm~2,143.2kg/hm~2,183.0kg/hm~2 and 159.8kg/hm~2.Thus,the rate of fertilizer application should be determined by the differences between rice species in order to decrease nitrogen fertilizer losses,improve the nitrogen fertilizer use efficiency and economic benefits of fertilizer.At different Nitrogen levels,the biomass and nitrogen uptake of different rice species were studied in the whole growth period.The results show that the change law of biomass is basically identical in the whole growth period and biomass are increasing with the growth period dalayed and reaching the highest amount at harvest.Jijing88 has strong absorptive capacity and high biomass and nitrogen uptake with hige nitrogen treatment,whereas Nongda19 has stronger ability to absorb nitrogen from soil than from nitrogen fertilizer which has higher biomass and nitrogen uptake at low nitrogen level.Analysis on dynamic changes of the SPAD value for 5 rice cultivars with different nitrogen treatment, the results showed that SPAD values of all species during the growing period are basically following the law of rising firstly and dropping later.Without nitrogen fertilizer in incubation period the SPAD value of Jijing88 was highest compared with other nitrogen treatment,and the SPAD value of Nongda 19 was second, the SPAD value of Fengyou307 was hightest until filling period.Under nitrogen level of 240 the SPAD values of Huijing7,Tongxi158 and Jijing88 changed little,however,the SPAD values of Nongda19 values decreased after the first growth.In incubation period the SPAD value of Fengyou307 was highest,until the filling stage the SPAD value of Nongda19 was highest,followed by Jijing88.Analysis on nitrogen use efficiency of 5 rice cultivars with different nitrogen treatment,the results showed that the nitrogen use efficiency of Jijing88 was highest at 46.4%under nitrogen level of 210,whereas the value of Fengyou307was lowest at 3.6%under nitrogen level of 150.The nitrogen partial factor productivity of Jijing88 reached the highest level of 118.5kg/kg under nitrogen level of 90,however,the value of Nongdal9was 43.1kg/kg which was the lowest under nitrogen level of 240.For Fengyou307 the agronomic efficiency of nitrogen fertilizer reached the highest level of 27.0kg/kg under nitrogen level of 120, compared with the agronomic efficiency of Nongda19 was 3.5 kg/kg under nitrogen level of 240.For Jinghui7 the physiological efficiency of N reached the highest level of 177.7 under nitrogen level of 90, whereas the value of Nongda19 was lowest at 17.7 under nitrogen level of 210.Therefor higher or lower application levels of nitrogen fertilizer went against improving nitrogen fertilizer use effency.The nitrogen partial factor productivity of 5 rice cultivars were decreasing significantly as nitrogen application ratio rising,meanwhile the agronomic efficiency of nitrogen fertilizer and the increase production ability of purity nitrogen per kg were rising firstly and dropping later.The physiological efficiency of N showed significant downtrend as nitrogen application ratio rising which showed the yield increase caused by nitrogen accumulation per kg was decreasing.